In vitro gas production by Maralfalfa (Pennisetum violaceum) and Taiwan (Cenchrus purpureus) grasses in the presence and absence of legumes

ABSTRACT Due to limited information and the need for nutritional enrichment, this study evaluated the chemical composition, digestibility, and gas production of Maralfalfa and Taiwan grasses alone and mixed (20% wt/wt) with the legumes gliricidia and leucaena. Six treatments were established: maralfalfa, maralfalfa + gliricidia, maralfalfa + leucaena, taiwan, taiwan + gliricidia, and taiwan + leucaena. Grasses were harvested 130 days after regrowth, and legumes were locally collected. Field-dried samples (n=4 per treatment) were analyzed for ash, neutral and acid detergent fibers, lignin, crude protein (CP), in vitro digestibility (IVDMD), and gas volumes (total, CO2, CH4) and proportions. Gliricidia and Leucaena had IVDMD/CP values of 81.0/16.7% and 90.5/25.0%, respectively. At 72h incubation, Taiwan mixtures with legumes had higher CP and IVDMD than grass alone, and at 24/48h, lower methane proportion (PCH4). With Gliricidia/Leucaena, Maralfalfa showed IVDMD of 66.2/68.1%, CP of 7.6/9.3%, PCH4 of 32.8/37.8%; Taiwan had IVDMD of 61.9/62.2%, CP of 11.2/12.8%, PCH4 of 21.0/22.1%. Thus, Maralfalfa mixtures showed the highest digestibility with low protein content, while Taiwan mixtures exhibited the lowest methane proportion with high protein. Increasing protein content is recommended to further probably reduce methane emissions.